Fugazzeta (Argentinian Stuffed Pizza)

To make the dough:

1. In a small bowl, sprinkle the yeast over the lukewarm water and stir to combine. Allow to sit at room temperature until frothy, about 10 minutes.
2. In the bowl of a stand mixer fitted with a dough blade or a large bowl, combine the flour, sugar, and salt.
3. Mix in the water with frothy yeast, milk and olive oil until dough comes together.
4. On a lightly floured surface, knead the dough until smooth and elastic.
5. Lightly oil a large bowl and add the dough, turning to coat. Cover and let rest until doubled, 1-2 hours.

To assemble:

1. In a large skillet, drizzle the 2 tablespoons (30 milliliters) olive oil over medium heat.
2. Add the thinly sliced onions to the pan. Cook, stirring occasionally, until softened but not brown.
3. Stir in the oregano, salt, and pepper. Remove from heat and set aside to cool slightly.
4. Preheat oven to 450˚F (230˚C). Grease a 14 inch (35.5 centimeter) round baking sheet or pizza pan with olive oil.
5. Divide the risen dough into 2 separate pieces, one slightly larger than the other. Cover the smaller piece of dough and place the larger piece on a lightly floured work surface.
6. Stretch the larger dough into a thin circle, about 12 inches (30.5 centimeters) wide, and place in the prepared pan.
7. Evenly cover with 3/4ths of the shredded mozzarella cheese, leaving a 1/2-1 inch (1.25-2.5 centimeter) border around the edges.
8. Stretch the smaller piece of dough into a circle large enough to cover the layer of cheese.
9. Fold the edges of the bottom circle over the top circle and pinch together to seal in the cheese.
10. Prick the top all over with a fork. Bake in the preheated oven for 5 minutes.
11. Remove the pizza from the oven and evenly top with the onions, Sprinkle with the remaining 1/4 mozzarella cheese. Lightly drizzle with olive oil.
12. Place back in preheated oven and bake until the crust is golden and the top layer of cheese is bubbly and browned, about 10-15 more minutes.
13. Serve the Fugazzeta warm from the oven.